The difference between doom and planar peat in tropical, temperate and latitude environment

1. The geology, botany and chemistry of selected
peat-forming environments from temperate
and tropical latitudes
CORNELIA C. CAMERON l, JOAN S. ESTERLE and CURTIS A. PALMER
Prepared by Andrea Hasbullah

2. OUTLINE
1. INTRODUCTION
2. WETLANDS - TYPES OF PEAT-FORMING ENVIRONMENTS
3. PEAT TYPES
4. SITES AND PROCESSES OF PEAT ACCUMULATION
5. TEMPERATE PEAT DEPOSITS
6. TROPICAL PEAT DEPOSITS
7. COMPARISON OF THE TEMPERATE AND TROPICAL EXAMPLES

3. 1. INTRODUCTION
• It is the intent of this paper to describe the several deposits typical of temperate and tropical latitudes selected as
representing principles of stratigraphic development, and to relate their organic and inorganic contents to their
geomorphology.
• The oldest "peat" in the United States appears to be an extensive bed of Pleistocene peat, which is almost a lignite, beneath
the sands of Trail Ridge in Bradford and Clay Counties, Florida (Rich, 1985).
• The Holocene deposits selected as examples for this paper have been examined in the field by at least one author.
• They represent organic sedimentation in peat-forming environments, have wide geographic range, are both ombrotrophic
(domed bogs) and minerotrophic, and are located in a variety of geologic settings.
• In this paper, we use the term "peat" for organic material having less than 25% ash on a dry basis; clayey peat has 25% to
50% ash, and peaty clay has greater than 50% ash.
• From our field studies and studies by others, we conclude that the major differences between peat deposits are the result of
the variety of plants from which peat is formed

4. 2. WETLANDS - TYPES OF PEAT-FORMING ENVIRONMENTS
• Bog is land that is wet, soft, and spongy, underlain by peat.
• Marsh is a saturated or shallow-water wetland fed by ground water, run- off, floods, and precipitation.
• In contrast, a swamp is a shallow-water wetland dominated by trees.
• The term "raised bog" is used for the domed peat deposit, which in the tropics may be covered with swamp forests, or
which in temperate climates may be covered by moss-heath vegetation with or without trees.
• The terms "fen" and "carr" used in the northern United States and Canada refer to a variety of marsh and a variety of
swamp, respectively.
• Peat bogs rich in nutrients are described as eutrophic, whereas those low in nutrients are called oligotrophic.
• Peatlands in which the source of water for the present surface vegetation emanates from the rock or mineral soil may be
known as minerotrophic, whereas those entirely dependent on precipitation as a source of water are known as
ombrotrophic.
• Water availability and nutrients help define the differences in wetlands and their vegetation.

5. 3. PEAT TYPES
• The most important characteristic reflecting plant type and degree of decomposition is texture (fiber size).
• The most decomposed peat is termed "sapric". Sapric peat is fine grained, is generally dark brown to black, and under
compression retains moisture and deforms as a paste.
• sapric peat is generally derived from small and easily decomposed algal and herbaceous aquatic plants of ponds and
marshes.
• Moderately decomposed peat is termed "hemic peat". Hemic peat is generally reddish brown to moderate brown but turns
dark brown upon exposure to air.
• The least decomposed peat type is termed "fibric". Fibric peat is reddish brown and composed predominantly of long
slender fibers.
• In temperate climates, fibric peat is generally derived from mosses and fine root systems of small shrubs growing in raised
bogs. In the tropics, woody fibric peats are derived predominantly from the extensive but slender root systems or horizontal
stems of trees (Anderson, 1964).

6. 4. SITES AND PROCESSES OF PEAT ACCUMULATION
• Sites for peat accumulation can
include locations where water collects
from valley head to the sea, thereby
incorporating a variety of terrains and
geologic and geographic settings
(Bellamy, 1972).
• The process of peat accumulation in
water-filled depressions is referred to
as lake-fill or terrestrialization when
the water body is replaced by peat.
• Peat accumulation on poorly drained,
flat surfaces also can continue where
the area is consistently saturated and
peat deposition overflows onto
mineral soil. This process is termed
paludification.
Fig. 1. Location and surficial geologic map of the bog on Great Cranberry Island, Maine,
showing location of peat core sites. (Modified from Raymond et al., 1987. )

7. Fig. 2 Schematic maps and cross sections of five stages in the development of domed peat
deposits in the northern United States. (Modified from Moore and Bellamy, 1974. )
5. COLD TEMPERATE PEAT DEPOSITS

8. 5. COLD TEMPERATE PEAT DEPOSITS
Fig. 3. Diagrammatic cross section of the bog on Great Cranberry Island, Maine, showing distri- bution of peat
types. Location of core sites in Fig. 1. (Modified from Raymond et al., 1987.)
• Bog on Great Cranberry Island, Maine - A domed
deposit that formed as sea level rose
• The raised Sphagnum bog on Great Cranberry
Island, Maine, is an example of a cold temperate
deposit that developed in a depression exposed to
rising sea level (Raymond et al., 1987).
• The deposit is small, less than 100 ha, and attains a
thickness of 8.5 m (Figs. 1, 2 ).

9. 5. WARM TEMPERATE PEAT DEPOSITS
Fig. 4. Surface map of the Snuggedy Swamp, South Carolina. (Modified from Staub and Cohen, 1979.)
• Peat deposits of the warm temperate southeast U.S. Atlantic and
Gulf Coastal Plains are like those of Maine and Minnesota in that
the processes of peat accumulation, namely terrestrialization and
paludification, are similar.
• Striking differences exist, however, in lack of dome convexity.
The peat surface is only slightly raised, the peat-forming
vegetation is more arboreal than herbaceous, and the peat is
generally a low-ash sapric variety.
• The deposits on the Coastal Plain of North Carolina, South
Carolina, Georgia and Florida illustrate these differences. Most
are more minerotrophic than ombrotrophic.
• Snuggedy Swamp represents freshwater peat accumulation in a
freshwater swamp/marsh complex surrounded by salt marsh fig.4

10. 6. TROPICAL PEAT DEPOSITS
Fig. 5. Vegetation map of peat forest communities in the Baram River area, Sarawak,
showing location of Tg Pasir transect between Baram River and Karap River, the cross
section of which is shown in Figs. 11, 12 transect. (Modified from Anderson, 1961. )
Fig. 6. Cross section of the Tg Pasir peat deposit showing cores that were drilled along the Tg Pasir transect
at sites 1-11 in the Baram River area, Sarawak. Location of transect shown in Fig. 5.

11. 7. COMPARISON OF THE TEMPERATE AND TROPICAL EXAMPLES
Table 1. *Analytical data on peat with 25% or less ash content given in wt.% on dry basis unless otherwise designated. Minnesota data are averages
for the Koochiching and Aitkin Counties and North Carolina data is average for the State. ~'References: (1) Cameron and Schruben, 1983; (2)
Heinselman, 1970; (3) Ingram, 1987; (4) Cohen, 1980; (5) Cameron et ah, 1987

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